Yes, I noticed the price on the Mesa tubes was... not cheap! Does anyone know, are these Siemens EL34's actually made by RFT?
From what I read, the later Siemens tubes were made by RFT in East Germany after the Western European companies stopped making tubes around 1980. Previously, Siemens tubes were made by companies like Mullard (which I think may have been owned by Philips by that time, so it could have been any of several Philips-owned plants).
Siemens was using their tubes for products like their medical equipment, so they may have tested them before boxing them up.
TubeDepot has the RFT made, Siemens branded EL34 for $165, which is a whole lot cheaper than Mesa, but I don't know if they're the same tube.
They’re most likely the same tube. In fact, the Siemens I bought from Mesa were $165 per matched pair at first, and based on the Tube Depot pictures, had the same base and shape.
I bought the Mesas because Mesa matches theirs and puts a color code on the tube so one tube can be replaced in a pair just by looking at the color code and using another with the same color code, instead of having to replace both tubes with a matched set.
It’s a nice convenience, but I wouldn’t spend the difference in price at this point.
One thing you may probably already know about the tube industry is that the tube manufacturers sometimes bought tubes from their competitors and re-branded them. So you’ll sometimes find Bugle Boys from Holland that were made by Mullard in England, etc. The same happened here.
The late ‘60s Westinghouse pair a friend sent me were clearly made by Tung-Sol, even though Westinghouse was still making tubes themselves. Sadly one of the tubes lost its vacuum seal and went bad, probably many years ago. The other tube is fine.
I wonder if Mesa is having to sift through these tubes and find those that fit their tolerance, since they usually only sell tubes that fit a certain spec so that no biasing is necessary? That's an area that PRS hit an absolute home run, IMO, putting bias test points on the back of the amp.
I sure agree about the PRS home run!
I read an article many years ago where Randall Smith said that early on he came up with the idea of a factory-set bias because players and even techs kept screwing up his amps by biasing tubes improperly. His customers didn’t want to pay a tech to adjust the bias, regardless. People would bring in an amp and complain that something was wrong, and he’d see that it simply wasn’t biased.
Nonetheless, there never was perfect tube matching, and there isn’t now except by pure luck — it’s always been ‘within tolerances’. This is true of all the tube suppliers. The matched pair of Mesa Siemens tubes I have in the HXDA measure several mV apart, and I bias them by finding a middle ground that’s ‘close enough’.
Mesa amps are biased pretty cold and will work with most decent tubes. I’ve used lots of non-Mesa branded tubes in my Mesas without issue since the ‘80s (in fact, I have the Telefunkens in my Fillmore, and the amp sounds significantly better to me).
Incidentally, Mesa is now branding Chinese-made 6L6 Psvane tubes as STR480s. I’ve been reading that these are truly well made tubes that compete with NOS, and sound great. There are also Western Electric, who make 300Bs here in the US and keep saying they’re going to make 12AX7s, and a high end manufacturer of (I think) KT77s in the Czech Republic.
So maybe there’s hope that down the road we’re going to see some great new tubes again.
One other note that interests me:
Eurotubes has JJ make 6L6s for Mesa combos with double Mica spacers. This is to cut down on tube rattle, and apparently it’s a good solution. I have a lot of respect for JJ tubes among modern manufacturers. I had a real problem with tube rattle in my Lone Star 2x12 combo; this was solved by installing the Telefunken cryo-treated 6L6s. I am not experiencing rattle with the NOS Siemens EL34s, either. But install current-make Russian or Chinese tubes and there’s that mechanical ringing in the top end that drives me bonkers.
I would never buy another combo amp for that very reason.